The emergence of antibiotic resistance has become a major clinical and public health threat worldwide.1.2 According to a recent report from the United Kingdom, if antimicrobial resistance continues to increase, 10 million people will die due to it annually by 2050, a mortality rate greater than that of cancer.1 Correct use of antibiotics and the development of novel antibiotics are both necessary to overcome this crisis.
World Health Organization (WHO) reported an extremely high resistant rates in Klebsiella pneumoniae, Escherichia coli and Staphylococcus aureus, which are common causes of hospital and community infections.4 K. pneumoniae and E. coli both belong to Enterobacteriaceae and have similar antibiotic resistance mechanisms.5 Understanding the antibiotic effectiveness against each resistant mechanism can help us to develop and use antibiotics. Traditionally, a large number of clinical drug-resistance isolates are collected and used for testing and screening antibiotics before going into clinical trials.6 However, the resistance mechanisms in clinical isolates usually are complex and not fully identified. It is difficult to verify which mechanism is actually involved or plays the major role in conferring the drug resistance. Without the certain information, it is also difficult to modify the antibiotic candidates for improving its antimicrobial activity in an efficient manner.